1911 Encyclopædia Britannica/Ceramics/Firing
425px|thumb|Page731, Volume_05 425px|thumb|Page731, Volume_05 425px|thumb|Page732, Volume_05 425px|thumb|Page732, Volume_05 The firin of pottery has become in modern times such a specialized branch of the manufacture that the student can onl be referred here to the technological works mentioned in the bibliography at the end of this article. It is, however, necessary that we should briefly describe the earlier forms of potters' kilns used by the nations whose pottery counts among the treasures of the collector and the antiquary. Here again we now know that the primitive types of kiln used by the potters of ancient Egypt or Greece have not vanished from the earth; it is only in the civilized countries of the modern world that they have been replaced by improved and perfected devices. The potters of the North-West Provinces of India use to-day a kiln practically identical with that depicted in severest silhouette on the rock tombs of Thebes; and the skilful Japanese remain content with a kiln very similar to the one shown in fig. 3. This Greek type of kiln was improved and enlarged by the Romans, and its use seems to have been introduced wherever pottery was made under probable construction of the kiln., their sway, for remains of Roman kilns have been found in many countries (see fig. 4). With the end of Roman dominance we have ample evidence that their technical methods fell into disuse, and the northern European potter of the period from the 6th to the 12th century had to build up his methods afresh, and improved kilns were invented. The general type of medieval potter's kiln is illustrated for us in the manuscrit of an Italian potter of the 16th century, now in the library of the Victoria and Albert MuseumI tre libri dell' Arte del Vasajo, by Cipriano Piccolpasso of Castel Durante, A.D. 1548. (fig. 5). Kilns of a different type, horizontal reverberatory kilns, were used for making the hard-fired pottery of Europe (Rhenish stoneware, &c.), as well as for Chinese porcelain and the earliest German porcelains. With the organization of pottery as a factory industry in the 18th century, improved kilns were introduced, and the type of kiln now so largely used in civilized countries is practically a vertical reverberatory furnace of circular section, from 10 to 22 ft. in diameter and of similar height, capable, therefore, of containing at one firing a quantity of pottery that would have formed the output of a medieval potter for a year. Every device that can be thought of for the better utilization of heat and its even distribution throughout the kiln or oven has been experimented with; and, though the results have been most successful from the point of view of the potter, even the most recent coal-fired ovens remain very wasteful types of apparatus, the amount of available heat being relatively small to the fuel consumption. Gasfired kilns and ovens are now being used or experimented with in every country, and their perfection, which cannot be far distant, will improve the most vital of the potter's processes both in certainty and economy. Page731-2048px-EB1911_-_Volume_05_5.djvu.jpg|FIG. 3.-Early Greek pottery-kiln, about 700-600 B.c. (from a painted votive tablet found at Corinth, now in the Louvre). The section shows the probable construction of the kiln. Page731-2048px-EB1911_-_Volume_05_6.djvu.jpg|Fig. 4.-Roman kiln found at Castor. The low arch is for the insertion of the fuel; the pots rested on the perforated floor, made of clay slabs; the top of the kiln is missing, -it was probably a dome. Page732-2048px-EB1911 - Volume 05 2.djvu.jpg| FIG. 5.-Two forms of Italian potter's wheels, about 1540.